1. Field of the Invention
The present invention relates to a golf club shaft and a golf club having the shaft.
2. Description of the Related Art
A golf club shaft having a carbon fiber has been commercially available. The shaft is also referred to as a carbon shaft. A carbon shaft having a light weight and a high strength can be manufactured by using the carbon fiber.
As a method for manufacturing the carbon shaft, a sheet winding process and a filament winding process have been known. Of these, the sheet winding process can produce shafts having different characteristics according to the disposal of prepreg sheets, the orientation of the carbon fiber and the type of the carbon fiber, or the like. The sheet winding process has a high degree of freedom in design.
Japanese Patent Application Laid-Open No. 2008-148757 (US2008/070716) discloses a shaft having a textile layer having warps and wefts. The textile layer has an axial fiber and a circumferential fiber. One of the warp and the weft is defined as the axial fiber, and the other is defined as the circumferential fiber.
Japanese Patent Application Laid-Open No. 2004-329738 (US2005/009621, US2007/072697 and US2009/305811) discloses a shaft having a plain weave textile layer. The warps and wefts of the textile layer are oriented obliquely to the longitudinal direction of the shaft.
Japanese Patent Application Laid-Open No. 2006-61473 discloses a shaft having a plain weave textile layer and a triaxial textile layer. The warps and wefts of the plain weave textile layer are oriented obliquely to the longitudinal direction of the shaft. The triaxial textile layer has wefts, first warps and second warps. The wefts of the triaxial textile layer are oriented parallel or perpendicularly to the longitudinal direction of the shaft.
Japanese Patent Application Laid-Open No. 2000-14843 (U.S. Pat. No. 6,270,426) discloses a shaft having a triaxial textile layer. The publication discloses the shaft in which the physical properties or the like of a fiber constituting the triaxial textile layer vary in the longitudinal direction of the shaft. The publication discloses the shaft having different triaxial textile layers located at positions (for example, a tip side, an intermediate portion and a butt side of the shaft) of the longitudinal direction of the shaft.
Japanese Patent Application Laid-Open No. 2000-288139 discloses a shaft which has a two-axis braided layer provided as an outermost layer and a three-axis braided layer provided on the inner side of the two-axis braided layer.
Japanese Patent Application Laid-Open No. 2008-307701 (US2008/311326) and Japanese Patent Application Laid-Open No. 8-131588 disclose a shaft having a straight layer and a hoop layer.